1. Field of the Invention
The present invention relates to a toner supply device in which a toner cartridge is detachably provided to be used in an image forming apparatus such as a printer, a copying machine, and a facsimile machine.
2. Description of the Related Art
A toner supply device for detachably joining a toner cartridge containing a toner to an apparatus main body to supply a toner into a toner hopper is used in an image forming apparatus such as an electrophotographic printer and copying machine, and a facsimile machine. An electrophotographic image forming apparatus draws a latent image on a photosensitive drum by a laser beam to develop the latent image with a toner. A developing container includes a toner hopper for storing and supplying the toner to be adsorbed on the surface of the photosensitive drum.
When the toner in the toner hopper is consumed by development, generally, the toner is supplied from the toner cartridge detachably joined with the image forming apparatus, into the toner hopper.
Further, when the image forming apparatus detects that the remaining amount of a developer in the toner cartridge becomes small, by a sensor or the like, the image forming apparatus displays a message to urge a user to change the toner cartridge. Furthermore, when the toner in the apparatus main body is decreased below a specified amount, the image forming apparatus stops printing. Thereafter, when the toner cartridge is changed and then the image forming apparatus can replenish the toner hopper with the toner, the image forming apparatus returns to a state in which printing can be performed.
In an image forming apparatus having a plurality of toner cartridges, when the remaining amount of respective toner cartridges becomes small, generally, a command to change the toner cartridge is issued to a user to enable individual change of the toner cartridge. Normally, it is rare that all cartridges are simultaneously changed and only one toner cartridge may be changed. However, as described above, in the apparatus with the toner cartridge which is changeable by a user operation, there has been a problem that a toner cartridge for which replacement is unnecessary is erroneously changed.
Thus, Japanese Patent Application Laid-Open No. 3-50568 discusses an apparatus for automatically changing a developing container. The apparatus selects an arbitrary developing container from a developing container containing device containing a plurality of developing containers to automatically transport it to an image forming apparatus. However, it is not preferable that a process cartridge, a developing container, and a toner cartridge are transported from an image-formable position to a detachable position to allow the toner cartridge to be changeable because it results in a large apparatus main body and an enlarged space necessary for maintenance.
Accordingly, a configuration is discussed in which a door is provided at a removal port of each of a plurality of toner cartridges, the door corresponding to the toner cartridge necessary for a change is unlocked, and the door is automatically opened, thereby notifying a user of a cartridge which needs changing. Further, U.S. Pat. No. 6,560,416 discusses a configuration in which a display device which outputs visual information is provided in each toner cartridge without providing a lock unit, thereby notifying a user of the absence of a toner.
However, in the U.S. Pat. No. 6,560,416, there are the following problems. Since the door of the toner cartridge, for which a change of the toner is necessary, is abruptly opened without confirmation by an operator, the toner cartridge may temporarily remain as it is while the door is open, which is not preferable.
Further, as discussed in U.S. Pat. No. 6,560,416, it is also conceivable that instead of automatically opening the door corresponding to the toner-absent cartridge, the display device which outputs visual information is provided without providing a lock unit, thereby notifying a toner absence state.
In this case, since the lock unit is not present, a user erroneously opens a door and image formation is stopped. Further, a plurality of displays needs to be provided, which increases manufacturing cost.
Furthermore, if a plurality of display devices is eliminated to prevent a cost increase, and in addition a lock device is provided on respective doors to prevent replacement of a toner cartridge for which a change of the toner is unnecessary, a useless operation is required such as a user searches an unlocked door.